The present invention generally relates to methods and apparatuses for recording and/or reproducing color video signals, and more particularly to a method and apparatus for recording an information signal so that the signal can be reproduced with a band which is wider than the transmission band of the information signal and for reproducing the signal with the band which is wider than the transmission band of the information signal, when recording and reproducing a color video signal by performing the processes of separating a luminance signal and a carrier chrominance signal from the color video signal, frequency-modulating the separated luminance signal, frequency-converting the separated carrier chrominance signal into a band which is lower than the band of the frequency modulated luminance signal, and frequency-division-multiplexing the frequency modulated luminance signal and the frequency converted carrier chrominance signal.
As is well known, an existing helical scan type video signal recording and reproducing apparatus (hereinafter simply referred to as a VTR) for home use separates a luminance signal and a carrier chrominance signal from a standard system (such as the NTSC system, PAL system, and SECAM system, for example) color video signal during a recording mode. The separated luminance signal is frequency-modulated, and the separated carrier chrominance signal is frequency-converted into a band which is lower than the band of the frequency modulated luminance signal. The frequency modulated luminance signal and the frequency converted carrier chrominance signal are frequency-division-multiplexed, and the frequency division multiplexed signal is recorded onto a magnetic tape by use of rotary heads. On the other hand, during a reproducing mode, the frequency division multiplexed signal is reproduced from the magnetic tape by use of rotary heads, and a reproduced frequency modulated luminance signal and a reproduced frequency converted carrier chrominance signal are frequency-selected from the reproduced frequency division multiplexed signal. The reproduced frequency modulated signal is frequency-demodulated sc as to obtain a reproduced luminance signal, and the reproduced frequency converted carrier chrominance signal is frequency-converted back into the original band so as to obtain a reproduced carrier chrominance signal. The reproduced luminance signal and the reproduced carrier chrominance signal are mixed so as to obtain a reproduced color video signal which is in conformance with the standard system.
In the above VTR for home use employing the low band conversion method of recording and reproduction, the recording and reproducing band of the luminance signal is limited to approximately 3 MHz (resolution of approximately 250 lines). A relative linear speed between the rotary head and the magnetic tape is set in accordance with the transmission band of the luminance signal. As a result, the diameter of a rotary drum which is mounted with the rotary heads can be set to a small value, and the VTR can be downsized. Further, the tape utilization efficiency is high.
In the VTR having such settings, the transmission band of the signal may be increased to a small extent in the future, as the performances of the magnetic tape and the rotary heads improve and the circuit technology progresses. However, under the condition of the limited relative speed between the rotary head and the magnetic tape, a rapid progress (for example, increasing the transmission band to an extent that is required to transmit a signal without limiting the original band of the signal) cannot be expected. The color video signal has a band of approximately 4.2 MHz in the case of the NTSC system and approximately 5.5 MHz in the case of the
or SECAM system. Hence, it is one of the objects of the VTR for home use to transmit the signal with fidelity and without limiting the original band of the signal, even under the condition of the limited relative speed between the rotary head and the magnetic tape.